1. Field of the Invention
This invention relates to an apparatus and a method for fitting multiple turbine blades (hereinafter called `blades`) radially to a disc.
2. Description of the Related Art
Known attachment structures for attaching multiple blades to a disc include for example the `Moving Blade Attachment Structure` disclosed in Japanese Utility Model Laid-Open Publication No. HEI 7-14102.
In the following description, a turbine consisting of blades attached to a disc will be referred to as a `turbine rotor`.
FIG. 11 hereof is a perspective view of part of a turbine rotor of related art. This turbine rotor 100 has a disc 101 and multiple blades 103 embedded in the outer circumferential face of the disc 101 so as to be restrained in the radial direction. Disc grooves 102 for attaching the blades 103 are formed in the outer circumferential face of the disc 101 with a uniform spacing in the circumferential direction, passing through the disc 101 diagonally with respect to its thickness direction. These disc grooves 102 are formed with wavy sides to support the blades 103 with respect to centrifugal forces acting radially outward on the blades 103 when they are rotated at high speeds. Fixing parts 103a with wavy sides for fitting into the disc grooves 102 are formed in base end parts of the blades 103. The turbine rotor 100 is constructed by the fixing parts 103a being fitted into the disc grooves 102 and tip end parts 104 of the blades 103 being connected together.
FIG. 12 is a view seen in the direction of the arrow 12 in FIG. 11 and illustrates that the disc grooves 102 are diagonal with respect to the thickness direction of the disc 101 and that the tip end parts 104, 104 are connected by mating projections and indentations.
With this turbine rotor 100, because the tip end parts 104 must be connected together and because the disc grooves 102 are formed diagonally, fitting the blades 103 to the disc 101 is not easy and requires skill.
While attachment structures for attaching blades to discs have been becoming more complex, improvements to fitting technology have lagged behind, and technology with which even an ordinary worker can fit blades to a disc easily has been being awaited.